Frustration in Excelsis 
"[@mana the immortal":](/1654438#comment_6887989
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That's actually a fascinating subject, because it's not that uncommon for different species to be able to interbreed --"[wolves and coyotes":](https://en.wikipedia.org/wiki/Coywolf), for instance, do so in the wild with some regularity, and the hybrids are fertile enough to have nearly supplanted both parent species in some parts of the Northeast Atlantic seaboard. It's almost always between species in the same genus, but even then there are exceptions -- domestic cats will fairly readily mate with "[leopard cats":](https://en.wikipedia.org/wiki/Leopard_cat) to produce fertile young, to the point that there's "[an entire cat breed":](https://en.wikipedia.org/wiki/Bengal_cat) that was developed by breeding the two animals together. There are even "[dromedary-llama hybrids":](https://en.wikipedia.org/wiki/Cama_(animal)) around, although they require artificial insemination due to size differences (dromedaries are quite a lot bigger than llamas).
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... to get back to the point, I don't think it's necessarily that far-fetched to assume different species can produce offspring. That being said, I would agree that beings as obviously different as equines and arthropod-equine chimeras are... well, unlikely to successfully produce young, at least outside of a laboratory setting. If I were to make my own AU or next gen (doubtful, but let's say), I would probably not make them able to reproduce without shapeshifting, which would likely result in the child being of whatever species the changeling shapeshifted into. But people are still perfectly free to decide whatever they want for their own works, of course.
On a more meta note, personal opinions aside, I don't find it too surprising that fanon offspring for horses and bug horses have been showing up. After all, draconies have been a thing since... well, since Sparity has been a thing, really. Changeponies are a much less extreme form of hybrids, and with draconies as common and generally accepted as they are, the addition of changeponies isn't comparatively a very big jump to make.
[@Background Pony #4BB9](/1654438#comment_6888046)
> We also have Minotaurs and Cockatrice which are hybrids according to old myths.
True, but they're likely not in the show. At least, there aren't any humans to be the minotaurs' progenitors.
Worldbuilding Addict
That's actually a fascinating subject, because it's not that uncommon for different species to be able to interbreed --
~
%(All links go to Wikipedia)
... to get back to the point, I don't think it's necessarily that far-fetched to assume different species can produce offspring. That being said, I would agree that beings as obviously different as equines and arthropod-equine chimeras are... well, unlikely to successfully produce young, at least outside of a laboratory setting. If I were to make my own AU or next gen (doubtful, but let's say), I would probably not make them able to reproduce without shapeshifting, which would likely result in the child being of whatever species the changeling shapeshifted into. But people are still perfectly free to decide whatever they want for their own works, of course.
On a more meta note, personal opinions aside, I don't find it too surprising that fanon offspring for horses and bug horses have been showing up. After all, draconies have been a thing since... well, since Sparity has been a thing, really. Changeponies are a much less extreme form of hybrids, and with draconies as common and generally accepted as they are, the addition of changeponies isn't comparatively a very big jump to make.
[@Background Pony #4BB9](/1654438#comment_6888046)
> We also have Minotaurs and Cockatrice which are hybrids according to old myths.
True, but they're likely not in the show. At least, there aren't any humans to be the minotaurs' progenitors.